Abstract: In a waveform equalization circuit, a digital signal is applied through a first network having a transfer function defined by four angular frequencies to one of the inversion and non-inversion input terminals of an amplifier and through a second network having a transfer function made up of a constant to the other input terminal, so that the digital signal subjected to waveform equalization is provided at the output terminal, whereby according to the transfer characteristic of the recording or reproducing system, the most suitable waveform equalization characteristic can be obtained with ease.

Abstract: A data reading device for reading out data modulated according to a system wherein the time ratio of low to high level signals is substantially unity employs a time ratio detector and an intermediate level detector. A comparator compares the reproduced output level with a synthesized signal which may represent a combination of the outputs of the time ratio detector and the intermediate level detector.

Abstract: A tone control circuit includes a variable gain amplifier circuit, a first mixer combining the variable gain amplifier output with a tone control circuit input and providing its output signal to the variable gain amplifier input, and a second mixer combining the outputs of the first mixer and variable gain amplifier. The mixers may be either adders or subtractors as long as the natural logarithm of the overall gain of the tone control circuit varies substantially linearly with changes in the feedback ratio of the variable gain amplifier.

Abstract: A tone control arrangement is disclosed which is suitable for use in various sound reproducing instruments and in which the signal-to-noise ratio of the reproduced sound can be improved by controlling the frequency response of the audible signal with a variable d.c. voltage source. Frequency response control by a single d.c. control voltage is achieved by connecting in series and in order a first mixer, passive circuit network having a signal transmission characteristic determined by the desired frequency response of the output sound signal to be reproduced, a multiplier and a second mixer. The inverting inputs of the first and second mixers both receive the output of the multiplier, while the non-inverting input of the first mixer receives the input audio signal. The non-inverting input of the second mixer receives either the output of the first mixer or the input audio signal. Finally, the second input to the multiplier is provided by a variable d.c. voltage source.

Abstract: A two-way CATV system having a substantial number of terminals incorporates a central processor and transmitter system which continually interrogates the terminals at high speed, monitoring changes of usage of premium programs and other data while also permitting central control of access to restricted premium programs. For inexpensive but reliable intercommunication, short, fixed word length digital messages are frequency multiplexed onto the cable in both upstream and downstream directions, and subscriber groups are controllably selected in turn, with each subscriber being scanned in what may be an arbitrary order by transmission of unique private messages which are recognized at the terminal and in response to which previously prepared fixed length messages are immediately transmitted in return.

Abstract: An output waveform of a manually operable tuning pulse generator of an electronic preset type tuning control device of a tuner using varactor diodes for a multi-band radio receiver is improved by using Schmitt trigger circuit means which may be provided with a trigger level checking circuit, both being provided as IC.

Abstract: A period-to-voltage converting device for producing an output voltage corresponding to the varying period of an input signal. The input signal is applied to a frequency divider and a simple logic circuit to control the charging and discharging of first and second capacitors. A charging circuit responsive to a first timing pulse having a width equal to half a period of an input signal charges the first capacitor to a predetermined voltage. A discharging circuit responsive to a second timing pulse having a width equal to the period of the input signal discharges the first capacitor at a constant rate. Another charging circuit responsive to a third timing pulse having a width equal to half a period of the input signal charges the second capacitor to the same voltage across the first capacitor, this voltage being the output voltage proportional to the period of the input signal.

Abstract: A speed-and-phase control circuit for a rotary machine. A frequency divider is responsive to an input signal whose frequency is proportional to the revolution number of the rotary machine. The frequency divider provides as a first output signal a frequency-divided version of the input signal. A logical circuit is responsive to the input signal and to the first output signal. The logical circuit provides in timed relationship first, second and third timing pulses. The pulse width of the first timing pulse and of the second timing pulse is equal to a half period of the input signal. The pulse width of the second timing pulse is equal to one period of the input signal.

Abstract: The auxilliary signal path in a compander system includes, in series, a first amplifier 7, a weighting function amplifier 8, and a detection circuit 9. The output of the latter controls the gain of a voltage-controlled variable gain circuit 11 also connected to the first amplifier output, and the integrated output of the variable gain circuit is fed back to the input of the first amplifier via a subtraction circuit 13 also supplied with the auxilliary signal path input. Alternatively, the first amplifier may comprise an operational amplifier, in which case the integrated signal is directly coupled to one of its inputs.

Abstract: A brushless d.c. motor includes a plurality of Hall elements 1-3 for detecting the relative positions of the rotor and stator poles, a comparator circuit 103 responsive to a bipolar input control signal A for generating an output signal B proportional to the absolute magnitude of signal A and an output signal D as a function of the polarity of signal A, a timing signal generator 104 for generating output signals E timed in relation to the Hall element outputs F and having a phase sequence in response to signal D, and a reversible current supply circuit 105 for driving a set of Y-connected stator windings 101 with currents C having a magnitude proportional to signal B and a phase sequence in accordance with signal E.